Method and apparatus for grading sand.



F, W. H. CLAY; METHOD ANDAPPARATUS FOR GRADING SAND APPLICATION men JULY 3|, I915.

L oness;

y TED STATES r trE- T Olaf-RICE,

manners w. n; CLAY, or EnGEwoonrARK, PENNSYLVANIA, nssrenon To :0. BAILY r Application filed July 31,1915. 7 Serial No. 42,935. a i

To all whom c'tmo'y concern a Be it known that I, FRANCIS; V7.v H..CLAY, a citizen of the United States; residing at Edgewood Park, in the State of Pennsylvania, have invented a certain new and use-" ful Method and Apparatus ior Gra dlng' Sand,of which the following is a spec1fica-.

tion.

My invention relates generally to the-Qart of separating masses of particles of'va'r ant' size into difierent grades; and; more part cu. larly it relates to the grindingart wherein it is necessary to carefully and uniformlygrade and separate grades of the abrasiye and arrange the grades in positlon for easy and efi'ective application to the ma:-

chine.

Heretofore the artificial grading at an plished by dropping the sandi in watengaiid'f allowing it to settle in a vertical direction-,2. which effects a stratum selection brought about by reason of the different, ratesof weight ratio. In certain refinements of this process, the body of waterhas been 1n the a tion of gravity in order to delay the time ofsettling,and thus partially suspend the plished by the use of'two'forces acting siparticle as to grade more slowly. Again;

there have been used devices which; em loyed the principle of varying the rate of how of the upwardly moving or suspendlng body of water at various heights, in order 1 totvary the resistance to falling, or the suspending force, in accordancewith the mass U andsurface of the particle.

esses the sand is graded 1n vertically super- In all such procposed layers, whichis an inconvenient arrangement, and moreover the sand is graded not'accorcling'to the actual mass of the particle, but according to the ratio between its superficial surface and Weight. AlsoQthis use of'gravity alone for separating results in av small separation of grades and the amount of separation has not "been under control.

In my'process an accurate gradingon the basis of actual mass, and a greater separatlon, in more convenient posltlon, 1s accommultaneously;=namely, the force of: gravity, and centrifugal force, or inertia. That is, I sub ect each particle, to the constant action of two forces operating in different Specification of Letters Eatent. Patented bra k t :1,

METHOD annarranarus roa GRADING 's-Aun directions, and thereby have a double separating efiect. Briefly, I employ centrifugal force combined with the force of gravity, in order to obtain an additional and larger and better separation, thanin the prior July 18 1916.

practice; These and other objects,- as will 7 hereinafter appear, may be attainedfby practice of the process withithe apparatus asv arranged for, illustrationiim the accomwhich-hoids-"the cone fixed on a shaft 3,. l ,4

to? which is attachd ,any convenient means for revolving,- as the pulley 5 operated by I cordfig The shaft '3, by plate 7 andrnut for grinding, for example, has been accomsupportsthe bott0m 9 of the grading and cylindrical portion 10 and generally conical portion 11, which ends at'thetop'in an aoutward flaring and receiving hopper I12aptravel of particles of difierent surface-to" V the-shaft 3. The sand may be fed in any v convenient way as by pipe 14 and may pass 1 meantime moved upward against the direc- 15, 16,17,dividing the vessel into storage compartments (18); (19), (20), (21).; Near 'the'topof the conical portion 11 I provide on the outside a circular overflow trough 2-2 At the bottom of the'cylindrical portion 10' I provide a series of concentric ring-walls having a continuation-in the form'of a circumferential shelf 22*inside thervessel 11 and a seriesof holes 22* to allow escape of Water and mud by overflow over the trough 22 into a surrounding circular troughf23 from which itymay be withdrawn in any convenient manner as by the valved pipe\24.

The storage compartments may be of any convenient'size, according ,to the use of the it apparatus, and the graded material may be" removedin any convenient manner. As'

here shown. for simplicity sake, Iprov'ide in the, bottom of each compartment a series of elongated circumferential small slots 26 which'may be normally covered by a flap valve in" the form of a rubber ring 25, and

this ring may be lifted to allow escape of sand and Water byvthe-upward movement ot a finger or plunger 27 and theusa n d draw off through a chute' 2 8. For convenience 1n emptyingthe vessel upon occasion, the con-' tral shaft 3" maybe hollow and have" open- 1110 lugs ('25!) through which the water may be emptied by the valve at the bottom.

In operation the vessel is completely filled with lluid of some sort, and it will be understood that as the vessel revolves the entire mass of this iiuid is in circular motion. The suspending medium may be air in dealing with some substances; but in dealing with sandjt is preferably water, as here shown (though sand may be raded dry in 1111). The sand in dropping through the water is separated laterally by centrifugaliorce according to the mass of each individual (particle, so that theclassified particles will rop into the horizontally separated storage compartments (18), (19), (20.), (21), as shown, and may be drawn oil as needed through the valves 25. Meantime mud and other matter not heavy enough to sink past the apron 22 before the centrifugal force carrles them out thereto, will be caught and drawn oil through the troughs 22 and 2391' in any other convenient way. i

Of course the theory of operationis not essential to my invention, but it is to 'be noted that the use of centrifugal force ermits of complete control of the classi ica tion. It is a familiar law of physics that a mass acted on simultaneously by two forces at an angle to each other, and free to move,

will be moved in direction and amount proportional to the diagonal'of a parallelogram (determined by the two forces. It will also be recalled that the surface of a particle varies with the square of the diameter; that the'cubic content varies with the cube of the diameter; that the centrifugal force tending to move it varies with the square of the velocity as well as with the actual mass of the particle.

A particle at the point 0 on the dotted line diagram-in the figure and in its suspended condition in the vessel 11, will be subjected to the vertical force of gravity 0 g, and simultaneously to the horizontal centrifugal force 0 'It would therefore in a certain time reach the point r by traveling approximately the line 0 r. The time of sinking through the water will determine the distance 0 g (since gravity is constant), but it will be noted also that the effective time of tion through the water increases with increasing density, in both the vertical and horizontal direction, so that the lateral re slstance also aids the separation into grades.

Under the conditions mentioned, by selecting the proper value of the speed, and therefore the centrifugal force, and supposing the grains of sand to be of uniform material (as crushed quartz), the lighter grams will travel farthest from the center and fall in the outer compartments, and the sand will be classified in a horizontal direction ac cording to mass. The entire vessel, will be designed to fit the particular conditions of the material being classified, and the use of the classified material.

Bythe apparatus shown for illustration, it will be seen that the sand maybe continuously introduced and continuously graded and continuously draivn oil, in any order desired, and each operation is subject to control without interfering with the other operations. For example, the amount of sand stored in the horizontally arranged storagecompartments, has no effect whatever upon the grading opcration; the lines 'of classification are changed by merely grading may be governed by the designed.

, speed of the vessel.

I believe I am the first to apply the use of centrifugal force to the grading of solid materials falling in a fluid. To the mechanic will occur many uses of the method and modifications of the suggested apparatus to fit conditions.

Having thus described my invention and illustrated its use, what I claim is the following:

l. The method of grading sand which comprises maintaining a body of, water in circular motion about a vertical axis, dropping the sand through said body of water fronrabove and separating the grades of sand horizontally in zones about the axis at equal elevation by the combined action of centrifugal force and gravity, substan tially as described.

2. The method of grading sand by dropping the sand in a body of water, meantime maintaining the body oi water in circular motion and thereby subjecting each particle oi sand to centrifugal force and the force of tate it about a vertical axis, mezins fer introducing the j sand into the water at the center of the top surface; and said' vessel being provided with partitions dividing the bott'onifportion into horizontal zones, sub staiitially as described. I u, 5. Sand grading apparatus comprising a circular vessel having concentric partitionmg Walls dividing ts bottom luto horizondescribed.

ta-l z'0nes,'means for suspending the vessel am for continually rotating 1t, means to 1ntroduce the sand at the center of the vessel, 7

and means to continually draw eff surplus water from the essel, substantla lly as Iii' testimony whereof I have hereunto signed my name;

- FRANCIS W. H. CLAY. 

